使用Linq 来解决Datatable 去除数据重复

在这也说明下，除此之外还可以通过 DataView 的方式来处理，当个人觉得这有点不好用。这里就不多作说明了

代码比较简单，直接看代码

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;

namespace DTS
{
class Program
{
static void Main(string[] args)
{
DataTable _dt = new DataTable();
_dt.Columns.Add("id", typeof(int));
_dt.Columns.Add("name", typeof(string));
_dt.Columns.Add("address", typeof(string));

DataRow _dr = _dt.NewRow();
_dr["id"] = 1;
_dr["name"] = "xiaodong";
_dr["address"] = "beijing";
_dt.Rows.Add(_dr);
_dt.Rows.Add(_dr.ItemArray);
_dt.Rows.Add(_dr.ItemArray);
_dr = _dt.NewRow();

_dr["id"] = 2;
_dr["name"] = "xiaodong";
_dr["address"] = "shanghai";
_dt.Rows.Add(_dr);
_dr = _dt.NewRow();

_dr["id"] = 3;
_dr["name"] = "xiaoming";
_dr["address"] = "guangdong";
_dt.Rows.Add(_dr);
_dr = _dt.NewRow();

_dr["id"] = 4;
_dr["name"] = "xudaxia";
_dr["address"] = "fujian";
_dt.Rows.Add(_dr);
_dt.Rows.Add(_dr.ItemArray);
Console.WriteLine("--------------------原来有重复数据的Table----------------------");
_dt.AsEnumerable().ToList().ForEach(
m=>
{
Console.WriteLine(m["id"].ToString() + "   " + m["name"].ToString() + "  " + m["address"].ToString());
});

Console.WriteLine("--------------------去除重复后的Table----------------------");
var _comPresult = _dt.AsEnumerable().Distinct(new DataTableRowCompare());
DataTable _resultDt = _comPresult.CopyToDataTable();

_resultDt.AsEnumerable().ToList().ForEach(
x =>
{
Console.WriteLine(x["id"].ToString() + "    " + x["name"].ToString() + "   " + x["address"].ToString());
});
Console.Read();
}
public class DataTableRowCompare : IEqualityComparer<DataRow>
{

#region IEqualityComparer<DataRow> 成员

public bool Equals(DataRow x, DataRow y)
{
return ((x.Field<int>("id") == y.Field<int>("id") && x.Field<string>("name") == y.Field<string>("name") && x.Field<string>("address") == y.Field<string>("address")));
}

public int GetHashCode(DataRow obj)
{
return obj.ToString().GetHashCode();
}

#endregion
}

}
}

昨晚（2015-10-11）想了个对以上代码优化的办法，事比较多早上补上：

public static DataTable DistinctSomeColumn(DataTable sourceTable, params string[] fieldName)
{
if (fieldName == null || fieldName.Length == 0) return sourceTable;
return sourceTable.AsEnumerable().Distinct(new ColumnEquals(fieldName)).CopyToDataTable();
}

public class ColumnEquals : IEqualityComparer<DataRow>
{
public ColumnEquals(string[] sArr)
{
_sArr = sArr;
}

private string[] _sArr;

public bool Equals(DataRow x, DataRow y)
{
return !_sArr.Any(p => !x[p].Equals(y[p]));
}

public int GetHashCode(DataRow dr)
{
return dr.ToString().GetHashCode();
}
}